The oldest roller coasters are believed to have originated from the so-called "Russian Mountains", which were specially constructed hills of ice, located especially around Saint Petersburg.[2] Built in the 17th century, the slides were built to a height of between 21 and 24 m (70 and 80 feet), consisted of a 50 degree drop, and were reinforced by wooden supports.

Some historians say the first roller coaster was built under the orders of Russia's Catherine the Great in the Gardens of Oranienbaum in Saint Petersburg in the year 1784. Other historians believe that the first modern roller coaster was built by the French. The Promenades Aeriennes in Parc Baujon and the Les Montagnes Russes à Belleville (The Russian Mountains of Belleville) were both constructed in Paris in 1817 and both featured wheeled cars securely locked to the track, guide rails to keep them on course, and higher speeds.[3]

The name Russian Mountains to designate a roller coaster is preserved in most Latin languages. However, the Russian term for roller coasters is "американские горки" ("amerikanskiye gorki"), which means "American Mountains".

In 1827, a mining company in Summit Hill, Pennsylvania constructed the Mauch Chunkgravity railroad, an 8.7-mile (14.0 km) downhill track used to deliver coal to Mauch Chunk (now known as Jim Thorpe), Pennsylvania.[4] By the 1850s, the "Gravity Road" (as it became known) was providing rides to thrill-seekers for 50 cents a ride. Railway companies used similar tracks to provide amusement on days when ridership was low.

Using this idea as a basis, LaMarcus Adna Thompson began work on a gravity Switchback Railway that opened at Coney Island in Brooklyn, New York in 1884.[5] Passengers climbed to the top of a platform and rode a bench-like car down the 600-foot (180 m) track up to the top of another tower where the vehicle was switched to a return track and the passengers took the return trip.[6] This track design was soon replaced with an oval complete circuit.[7] In 1885, Phillip Hinkle introduced the first full-circuit coaster with a lift hill, the Gravity Pleasure Road, which was soon the most popular attraction at Coney Island.[7] Not to be outdone, in 1886 LaMarcus Adna Thompson patented his design of roller coaster that included dark tunnels with painted scenery. "Scenic Railways" were to be found in amusement parks across the county,[7] with Frederick Ingersoll's construction company building many of them in the first two decades of the 20th century.

By 1919, the first underfriction roller coaster had been developed by John Miller.[8] Soon, roller coasters spread to amusement parks all around the world. Perhaps the best known historical roller coaster, The Cyclone, was opened at Coney Island in 1927.

The Great Depression marked the end of the first golden age of roller coasters, and amusement parks in general went into decline. This lasted until 1972, when The Racer was built at Kings Island in Mason, Ohio (near Cincinnati). Designed by John Allen, the instant success of The Racer began a second golden age, which has continued to this day.

In 1959 Disneyland introduced a new design breakthrough with Matterhorn Bobsleds. This was the first roller coaster to use a tubular steel track. Unlike wooden coaster rails, which are generally formed using steel strips mounted on laminated wood, tubular steel can be easily bent in any direction, which allows designers to incorporate loops, corkscrews, and many other maneuvers into their designs. Most modern roller coasters are made of steel, although wooden coasters are still being built.

There are several explanations of the name roller coaster. It is said to have originated from an early American design where slides or ramps were fitted with rollers over which a sled would coast.[7] This design was abandoned in favor of fitting the wheels to the sled or other vehicles, but the name endured.

Another explanation is that it originated from a ride located in a roller skating rink in Haverhill, Massachusetts in 1887. A toboggan-like sled was raised to the top of a track which consisted of hundreds of rollers. This Roller Toboggan then took off down gently rolling hills to the floor. The inventors of this ride, Stephen E. Jackman and Byron B. Floyd, claim that they were the first to use the term "roller coaster".[6]

The term jet coaster is used for roller coasters in Japan, where such amusement park rides are very popular.[9]

In many languages, the name refers to "Russian mountains". Contrastingly, in Russian, they are called "American mountains". In Scandinavian languages, the roller coaster is referred as "mountain-and-valley railway"

The cars on a typical roller coaster are not self-powered. Instead, a standard full circuit coaster is pulled up with a chain or cable along the lift hill to the first peak of the coaster track. The potential energy accumulated by the rise in height is transferred to kinetic energy as the cars race down the first downward slope. Kinetic energy is then converted back into potential energy as the train moves up again to the second peak. This hill is necessarily lower, as some mechanical energy is lost to friction.

Not all rides feature a lift hill, however. The train may be set into motion by a launch mechanism such as a flywheel launch, linear induction motors, linear synchronous motors, hydraulic launch, compressed air launch or drive tire. Such launched coasters are capable of reaching higher speeds in a shorter length of track than those featuring a conventional lift hill. Some roller coasters move back and forth along the same section of track; these are known as shuttles and usually run the circuit once with riders moving forwards and then backwards through the same course.

A properly designed ride under good conditions will have enough kinetic, or moving, energy to complete the entire course, at the end of which brakes bring the train to a complete stop and it is pushed into the station. A brake run at the end of the circuit is the most common method of bringing the roller coaster ride to a stop. One notable exception is a powered roller coaster. These rides, instead of being powered by gravity, use one or more motors in the cars to propel the trains along the course.

If a continuous-circuit coaster does not have enough kinetic energy to completely travel the course after descending from its highest point (as can happen with high winds or increased friction), the train can valley: that is, roll backwards and forwards along the track, until all kinetic energy has been released. The train will then come to a complete stop in the middle of the track. This, however, works somewhat differently on a launched coaster. When a train launcher does not have enough potential energy to launch the train to the top of an incline, the train is said to roll back.

In 2006, NASA announced that it would build a system using principles similar to those of a roller coaster to help astronauts escape the Ares I launch pad in an emergency.[10]

Many safety systems are implemented in roller coasters. One of these is the block system. Most large roller coasters have the ability to run two or more trains at once, and the block system prevents these trains from colliding. In this system, the track is divided into several sections, or blocks. Only one train at a time is permitted in each block. At the end of each block, there is a section of track where a train can be stopped if necessary (either by preventing dispatch from the station, closing brakes, or stopping a lift). Sensors at the end of each block detect when a train passes so that the computer running the ride is aware of which blocks are occupied. When the computer detects a train about to travel into an already occupied block, it uses whatever method is available to keep it from entering. The trains are fully automated.

The above can cause a cascade effect when multiple trains become stopped at the end of each block. In order to prevent this problem, ride operators follow set procedures regarding when to release a newly loaded train from the station. One common pattern, used on rides with two trains, is to do the following: hold train #1 (which has just finished the ride) right outside the station, release train #2 (which has loaded while #1 was running), and then allow #1 into the station to unload safely.

Another key to safety is the control of the roller coaster's operating computers: programmable logic controllers (often called PLCs). A PLC detects faults associated with the mechanism and makes decisions to operate roller coaster elements (e.g. lift, track-switches and brakes) based on configured state and operator actions. Periodic maintenance and inspection are required to verify structures and materials are within expected wear tolerances and are in sound working order. Sound operating procedures are also a key to safety.

Roller coaster design requires a working knowledge of basic physics to avoid uncomfortable, even potentially fatal, strain to the rider. Ride designers must carefully ensure the accelerations experienced throughout the ride do not subject the human body to more than it can handle. The human body needs time to detect changes in force in order to control muscle tension. Failure to take this into account can result in severe injuries such as whiplash. The accelerations accepted in roller coaster design are generally in the 4-6Gs (40–60 m s−2) range for positive vertical (pushing you into your seat), and 1.5-2Gs (15–20 m s−2) for the negative vertical (flying out of your seat as you crest a hill).[citation needed] This range safely ensures the majority of the population experiences no harmful side effects. Lateral accelerations are generally kept to a minimum by banking curves. The neck's inability to deal with high forces leads to lateral accelerations generally limited to under 1.8Gs.[citation needed] Sudden accelerations in the lateral plane result in a rough ride.

Despite safety measures, accidents can, and do, occur.[11] Regulations concerning accident reporting vary from one authority to another. Thus in the USA, California requires amusement parks to report any ride-related accident that requires an emergency room visit, while Florida exempts parks whose parent companies employ more than 1000 people from having to report any accidents at all. Rep. Ed Markey of Massachusetts has introduced legislation that would give oversight of rides to the Consumer Product Safety Commission (CPSC).

Ride accidents can also be caused by riders themselves or ride operators not following safety directions properly, and, in extremely rare cases, riders can be injured by mechanical failures. In recent years, controversy has arisen about the safety of increasingly extreme rides. There have been suggestions that these may be subjecting passengers to translational and rotational accelerations that may be capable of causing brain injuries. In 2003 the Brain Injury Association of America concluded in a report that "There is evidence that roller coaster rides pose a health risk to some people some of the time. Equally evident is that the overwhelming majority of riders will suffer no ill effects."[12]

A similar report in 2005 linked roller coasters and other thrill rides with potentially triggering abnormal heart conditions that could lead to death.[13] Autopsies have shown that recent deaths at various Disney parks, Anheuser-Busch parks, and Six Flags parks were due to previously undetected heart ailments.

Statistically, roller coasters are very safe compared to other activities. The U.S. Consumer Product Safety Commission estimates that 134 park guests required hospitalization in 2001 and that fatalities related to amusement rides average two per year. According to a study commissioned by Six Flags, 319 million people visited parks in 2001. The study concluded that a visitor has a one in one-and-a-half billion chance of being fatally injured, and that the injury rates for children's wagons, golf carts, and folding lawn chairs are higher than for amusement rides.[14]

Steel coasters have tubular steel tracks, and are known for their smooth ride and often convoluted shapes that frequently turn riders upside-down via inversions. Wooden coasters have flat steel tracks, and are typically renowned by enthusiasts for their rougher ride and "air time" produced by negative G-forces when the train reaches the top of hills along the ride. There are also hybrid roller coasters which combine a steel structure with flat tracks, or a wooden structure with tubular tracks.

Modern roller coasters take on many different forms. Some designs take their cue from how the rider is positioned to experience the ride. Traditionally, riders sit facing forward in the coaster car, while newer coaster designs have ignored this tradition in the quest for building more exciting, unique ride experiences. Variations such as the stand-up roller coaster and the flying roller coaster position the rider in different ways to provide different experiences. Stand-up coasters involve cars that have the riders in a standing position (though still heavily strapped in). Flying coasters have the riders hanging below the track face-down with their chests and feet strapped in. Vekoma "Flying Dutchman" coasters have the riders starting out sitting above the track, then they fully recline so that the riders are looking at the sky. Eventually, they twist into the "flying" position. B&M flying coasters have the riders hanging below the track like in an inverted (hanging) coaster. To go into the flight position, the section of the car where the riders' feet are raised to the track. That way, they start in the flight position. In addition to changing rider viewpoint, some roller coaster designs also focus on track styles to make the ride fresh and different from other coasters.

See Roller coaster elements for the various parts of a roller coaster and the types of thrill elements that go into making each roller coaster unique.

Several height classifications have been used by parks and manufacturers for marketing their roller coasters. As a result, some classifications are not always agreed upon or defined consistently throughout the roller coaster community.

One classification known as a kiddie coaster is a roller coaster specifically designed for younger riders including toddlers. Following World War II, parks began pushing for more of them to be built due to the height and age restrictions of standard designs. Companies like Philadelphia Toboggan Company (PTC) developed scaled-down versions of their larger models to accommodate the demand. These typically featured lift hills smaller than 25 feet (7.6 m), and still do today. The rise of kiddie coasters soon led to the development of "junior" models that had lift hills up to 45 feet (14 m). A notable example of a junior coaster is the Sea Dragon – the oldest operating roller coaster from PTC's legendary designer John Allen – which opened at Wyandot Lake in 1956 near Powell, Ohio.[6]

A Hyper Coaster is a type of roller coaster with a height or drop that ranges from 200 feet (61 m) to 299 feet (91 m) and completes a full circuit. The first roller coaster to be classified as a hyper coaster is Magnum XL-200 at Cedar Point designed by Arrow Dynamics. Since its debut, hyper coasters have become one of the most predominant types of roller coasters worldwide. Bolliger & Mabillard and Intamin are the leading manufacturers of this type.

A Giga Coaster is a type of roller coaster with a height or drop that ranges from 300 feet (91 m) to 399 feet (122 m) and completes a full circuit. The term was coined by a Cedar Point and Intamin partnership following the construction of Millennium Force. The only other giga coaster built by the same company is Intimidator 305 at Kings Dominion.[15] Although Morgan and Bolliger & Mabillard have not used the term giga,[16] both have a roller coaster in this class.

A Strata Coaster is a type of roller coaster with a height or drop that is 400 feet (120 m) or more and completes a full circuit. Only two strata coasters have been built, both of which utilize Intamin's hydraulically launched accelerator coaster design. The first was Top Thrill Dragster at Cedar Point, which opened in 2003 at a height of 420 feet (130 m). The second was Kingda Ka at Six Flags Great Adventure, which opened in 2005 at a height of 456 feet (139 m) – also making it the tallest roller coaster in the world. Superman: Escape From Krypton at Six Flags Magic Mountain was the first to break the 400-foot (120 m) barrier, but since it is a shuttle roller coaster that does not complete a full circuit and its drop is only 328 feet (100 m), some do not classify it as a strata roller coaster.[who?]